content flashcard for chapter 2

thin clients

• always relies on a connection to a remote server for it to work

• requires very few local resources

• relies on good network connection to work

• data is stored on remote server

thick clients

• can run some of the features of the software even when not connected to the server

• relies heavily on local resources

• more tolerant of a slow connection

• can store data locally

pros of cloud

• client files can be accessed from anywhere in the world with internet connection

• no need to carry external storage devices

• back up of data

neg of cloud

• doesnt work under no internet

• cost can be high if large storage capacity is needed

public cloud

storage environment where the client and storage provider are different companys

private cloud

storage provided by a dedicated environment behind company firewall

where client and cloud storage provider are one entity

how bluetooth works

• receives and sends radio waves in a band of 79 different frequencies

• each pair in a sperate channel

• when a device needs to communicate it selects one of these channels if occupied it picks another randomly

• is a wpan wireless personal area network

what is spread spectrum frequency hopping

• when a device needs to communicate it selects one of these channels if occupied it picks another randomly

when is bluetooth useful

transferring between one or two devices which are less then than 30 seconds metre

when speed isnt critical

using low bandwidth applications

twisted pair key facts

used in lans

two types shielded and unshielded

shielded is commercial use

unshielded is residential use

cons of twisted pair

lowest data transfer rate

suffers from external interference

cons and pros of coaxical cables

suffer from signal attenuation

offer best anti jamming technology

used in mans

two types of fibre optic cables

single mode-less light reflections - telecommunications- travel further

multi core - more light reflections - lan -shorter distances

when to use wireless

• easier to expand

• increased mobility when using a device

• less secure

• more interreference

when to use wired

• more reliable

• tends to be cheaper

• tripping hazards

what is a hub

• connected to a number of devices to form a lan

• takes a data packet at a single point and sends it to all connected devices

• waste of bandwidth

• not secure

what is a switch

• they connect to a number of devices to form a lan

• checks the data packet

• sends to required computers using mac addresses

• can be wireless or wired

what is a repeater

• combat signal attenuation over long distances by amplifying signals

what is a bridge

devices interconnecting lans that use the same protocol

what is a router

forwards packets from one network to another via public ip

route traffic form one network to another

can join lan and wan

as a firewall

how a router sends a packet

• using public ip address to fidn the right switch

• if the switch doesn’t have matching device to mac address the router tries another switch

what is a gateway

convert one protocol to another

acts as an entry point and exit point to networks

what is a modem

• modulator demodulator

• converts digital to analogue and back

• will connect to public infrastructure and supply ethernet output to router

differences between gateway and router

does support dynamic routing vs doesnt

converts protocols vs fowards packets on same networks

what is a NIC

network interface card

contain mac address

needed to connect to the internet

what is a node in ethernet

any device on the lan

what is a medium in ethernet

path used by the lan devices such as an ethernet cable

what is a frame

data transmitted in frames which are made up of source address and destination address

when may an ip conflict happen in ethernet

when devices on the same ip address most likely to happen when a dynamic ip address is assigned by a network when a static ip address is already using the same ip

when do collisions happen

when ethernet broadcasts a message at the same time

how csma/cd works

when a frame is sent there is a change in the voltage of the ethernet cable the computer listens to the signal its sending if its not correct its stops sending the frame transmits a jam signal and waits a random period of time before sending again

what is voip

voice over internet protocol

data is split into packets sent over the network in the fastest route

what is pstn

always open connection

through dedicated circuit thats constantly maintained

wahts the ipv4 rangesa and use case

0000 to 127.255.255.255-very large networks

128.0.0.0 to 191.255.255.255-medium size

192.0.0.0 to 223.255.255.255-small networks

224.0.0.0 to 239.255.255.255-multi-cast

240.0.0.0 to 255.255.255.255-experimetal

whats the first part and the second part of an ipv4 address

first-net id

second-hostid